Application of LaBr detector for neutron resonance densitometry

Tsuchiya, Harufumi ; Harada, Hideo   ; Koizumi, Mitsuo ; Kitatani, Fumito  ; Takamine, Jun ; Kureta, Masatoshi   ; Iimura, Hideki  ; Becker, B.*; Kopecky, S.*; Schillebeeckx, P.*

In order to quantify nuclear materials in melted fuels in the reactors of the Fukushima Daiichi Nuclear Power Plants, a concept of neutron resonance densitometry has been proposed. The neutron resonance densitometry is a non-destructive technique, utilizing both neutron resonance transmission analysis and neutron resonance capture analysis. Aiming at efficiently measuring capture rays under high background environment originating from Cs, we plan to utilize a new type of -ray detector consisting of a cylindrical LaBr scintillator and a tube type of LaBr scintillator. One of the main purposes of employing the new type LaBr detector is to suppress the Compton edge originating from Cs. To show the LaBr-detector abilities, GEANT4 simulations were made under reasonable assumptions. Then, we estimated attainable statistical accuracy of the 478-keV -ray detection assuming B concentration in the melted fuel. In addition, we conducted at JRC-IRMM a neutron capture -ray experiment using a LaBr detector and a germanium detector. This experiment has an aim of showing that a LaBr detector is applicable to measurement of prompt rays in NRD. In this presentation, we provide the experimental results performed at JRC-IRMM as well as the GEANT4 simulations. Then we discuss the capability and application of the proposed LaBr detector for neutron resonance densitometry.